Summary Core A measures serum, serum ultrafiltrate, plasma and urine stone risk chemistries and calculates urine supersaturations for patients studied in Projects 1 and 2. These measurements are used for fulfillment of aims within all four central program project objectives. Upper limit of metastability (ULM) for calcium oxalate and calcium phosphate in urine will be measured for Project 1. Core A will also measure plasma renin for Project 1. Blood and urine samples are processed and shipped for assay of lithium done in Core B, measurement of inflammatory markers in Core D and measurement of intact parathyroid hormone (PTH), aldosterone, 25(OH)- vitamin D and 1,25-dihydroxyvitamin D (performed by LabCorp). Urine exosomes will be prepared for molecular expression studies of renal ion transporter proteins. Aliquots of all blood and urine specimens are stored at -80C for future use. All laboratory data from Core A for all projects are consolidated into a single database with daily backup for security and ease of analysis. Ultimately, data from the other projects and cores (e.g. histology, biopsy, stone analysis etc.) will be consolidated into our database so that it can be analyzed along with serum and urine data.